Preparation method of bone nail and bone nail

Abstract

The invention discloses a preparation method of a bone nail and the bone nail, and the method comprises the following steps: pretreating a silk raw material to obtain a target silk protein solution; the target silk protein solution is subjected to shaping, drying demolding and first-time machining, and an initial silk protein bar is prepared; performing wet stretching and fixing process treatment on the initial silk protein bar to obtain a treated silk protein bar; and carrying out secondary machining on the treated fibroin bar to obtain the target fibroin bone nail. According to the application, the silk protein bar is subjected to wet stretching fixing process treatment, and the target silk protein bone nail prepared based on the stretched silk protein bar has the hydration response shrinkage characteristic, can slowly shrink in vivo, provides compression force, promotes bone restoration and stimulates bone healing, and is wide in applicability and low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of bone nail preparation, and particularly to a method for preparing a bone nail and a bone nail. Background Art

[0002] The bone nails in the prior art do not have shrinkability, and there is a problem that they cannot adapt to the length change or load demand change that may occur during the fracture healing process. Summary of the Invention

[0003] In view of the above problems, the purpose of the present invention is to provide a method and a bone nail that can prepare a bone nail with shrinkability, and the technical solutions are as follows:

[0004] On the one hand, a method is provided, in which silk raw materials are pretreated to obtain a target silk protein solution;

[0005] The target silk protein solution is successively subjected to shaping, drying and demoulding, and first machining to obtain an initial silk protein bar;

[0006] The initial silk protein bar is subjected to a wet stretching and fixing process treatment to obtain a stretched silk protein bar;

[0007] The stretched silk protein bar is subjected to second machining to obtain a target silk protein bone nail.

[0008] In an exemplary embodiment, the wet stretching and fixing process treatment includes:

[0009] The initial silk protein bar is moistened with ultrapure water;

[0010] The initial silk protein bar is fixed on a tensile testing machine, and the initial silk protein bar is stretched according to target stretching parameters; the target stretching parameters include: stretching length and stretching speed.

[0011] In an exemplary embodiment, after stretching the initial silk protein bar according to the target stretching parameters, the method further includes:

[0012] The stretched silk protein bar is fixed on the tensile testing machine, and the stretched silk protein bar is dried.

[0013] In an exemplary embodiment, the pretreatment of the silk raw materials to obtain the target silk protein solution includes:

[0014] The cocoon is degummed to obtain degummed silk;

[0015] The degummed silk is cleaned to obtain cleaned silk;

[0016] Provide a solvent to dissolve the cleaned silk to obtain an initial silk protein solution;

[0017] Purify the initial silk protein solution to obtain the target silk protein solution.

[0018] In an exemplary embodiment, the degumming treatment of the cocoon to obtain the degummed silk includes:

[0019] Provide an alkaline solution;

[0020] Place the cocoon in the alkaline solution and heat it to boiling for degumming to obtain the degummed silk.

[0021] In an exemplary embodiment, the alkaline solution includes an aqueous sodium carbonate solution;

[0022] The mass concentration of sodium carbonate in the aqueous sodium carbonate solution is 0 - 100 g / L;

[0023] The mass ratio of the cocoon to the volume of the aqueous sodium carbonate solution is 10:(1 - 100) g / L.

[0024] In an exemplary embodiment, the solvent includes an aqueous lithium bromide solution;

[0025] The mass concentration of lithium bromide in the aqueous lithium bromide solution is 0.01 - 2 g / mL.

[0026] In an exemplary embodiment, the purification treatment includes:

[0027] Provide a dialysis bag and a centrifuge tube;

[0028] Transfer the initial silk protein solution into the dialysis bag, place the dialysis bag containing the initial silk protein solution in deionized water, and perform dialysis treatment on the initial silk protein solution to obtain a dialyzed silk protein solution;

[0029] Transfer the dialyzed silk protein solution into the centrifuge tube;

[0030] Place the centrifuge tube containing the dialyzed silk protein solution in a centrifuge for centrifugation, and collect the supernatant.

[0031] In an exemplary embodiment, after collecting the supernatant, the method further includes:

[0032] Concentrate the supernatant to obtain the target silk protein solution, and the mass fraction of silk protein in the target silk protein solution is 0.5% - 50%.

[0033] On the other hand, the present invention also provides a bone nail prepared by any of the above methods.

[0034] The present invention discloses a method for preparing a bone nail, which includes pre-treating silk raw materials to obtain a target silk protein solution; shaping, drying and demolding, and first machining the target silk protein solution to prepare an initial silk protein rod; performing a wet stretching and fixing process on the initial silk protein rod to obtain a processed silk protein rod; and performing second machining on the processed silk protein rod to obtain a target silk protein bone nail. Through the wet stretching and fixing process on the silk protein rod, the target silk protein bone nail prepared based on the stretched silk protein rod has a hydration-responsive shrinkage property, can slowly shrink in vivo, provide compressive force, promote bone reduction, stimulate bone healing, has wide applicability and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings according to these drawings without creative efforts.

[0036] Figure 1 is a flowchart of a method for preparing a bone nail provided by an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of a stretching process provided by an embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of the length comparison of a target silk protein bone nail before and after being immersed in water provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0040] Fracture is one of the most frequently encountered traumas in our daily life, and bone nails are basically used in every fracture surgery. The preferred implant in fracture fixation surgery is usually a bone nail made of hard metal materials (such as stainless steel and titanium alloy, etc.). However, three defects of this kind of bone nail have been exposed in long-term clinical applications: First, the internal fixation of metal screws often requires a second operation on the patient to remove them, which may damage the articular cartilage and also makes the patient bear greater pain and the burden of surgical costs. Second, the mechanical strength of metal materials is much higher than that of human bones, and there is a stress shielding effect, which will hinder fracture healing. Third, some metal materials cannot be used for magnetic resonance and computed tomography scans after surgery. Even if some materials such as titanium alloy can be scanned, obvious artifacts will still exist, seriously affecting the imaging effect. In view of the disadvantages of current metal materials, materials such as magnesium metal, inorganic hydroxyapatite, polylactic acid, poly-L-lactic acid, and poly-D-lactic acid have been used to manufacture absorbable screws for the human body. Although such materials are beneficial for fracture treatment, they may cause inflammation and incomplete bone development. Similarly, these materials cannot achieve good adaptation between mechanical properties and degradation properties. Under normal circumstances, when a fracture occurs, the body will initiate a natural healing process, including inflammatory response, cartilage formation, bone calcification, and finally bone remodeling. To support this complex biological process, it is necessary to ensure the stability of the fracture site and an appropriate mechanical environment. Traditional bone nails can provide stability, but they are usually static and cannot adapt to the length changes or changes in load requirements that may occur during the fracture healing process. With the in-depth understanding of the fracture healing mechanism, research shows that moderate dynamic compression can promote fracture healing. Therefore, there is a need to design an absorbable shrinkable bone nail for the human body. The applicable range of the shrinkable bone nail is wide (such as transverse fractures, etc.), and it can stimulate and accelerate bone reduction, promote fracture healing, and maintain fracture stability to prevent complications by providing compressive stress.

[0041] The embodiment of the present application provides a preparation method of a bone nail. Specifically, please refer to Figure 1 , as Figure 1 shown, this method includes the following steps:

[0042] Step S1: Pretreat the silk raw material to obtain a target silk fibroin solution.

[0043] Specifically, the silk raw material is a mulberry silk cocoon from which the silkworm pupae have been removed. This silk raw material consists of two proteins, fibroin and sericin. Among them, fibroin is the main component of the silk raw material, accounting for 70% - 80% of the total mass of the silk raw material, and sericin accounts for 20% - 30% of the total mass of the silk raw material. Compared with common natural (such as collagen) and synthetic (such as polycaprolactone, polylactic acid, etc.) biomaterials, fibroin has unique and excellent mechanical properties, achieving a perfect balance between strength and toughness. Fibroin has characteristics such as high strength, controllable biodegradability, hemostasis, no cytotoxicity, low antigenicity, and non-inflammability, and has a wide range of applications in the biomedical field. Fibroin can be processed into different material forms suitable for biomedical applications. Currently, it is widely used in related fields such as wound dressings, tissue engineering, and drug delivery, such as the regeneration of load-bearing tissues like cartilage, ligaments, and bones, surgical sutures, porous scaffolds, films, medical hydrogels, etc. In the embodiments of the present application, the sericin in the silk raw material should first be removed to obtain fibroin, and then processed to obtain the target fibroin solution.

[0044] Step S2: The target fibroin solution is successively subjected to shaping, drying and demoulding, and first machining to obtain an initial fibroin rod.

[0045] In specific implementation, it can be prepared according to the actual required size and shape to obtain an initial fibroin rod.

[0046] Step S3: The initial fibroin rod is subjected to a wet stretching and fixing process treatment to obtain a stretched fibroin rod.

[0047] Specifically, the present application takes into account that the most significant difference between spider silk and silk is that the former exhibits supercontraction. When natural spider silk fibers are immersed in polar solvents (especially water) or exposed to solvent vapors, they contract along their long axes to shorten the fibers. This supercontraction phenomenon is mainly caused by the reduction in the orientation of oriented molecular chains in the amorphous region. Natural silk cannot exhibit significant contraction behavior under similar conditions. Simulating the molecular structure of spider silk can achieve the self-contraction performance of fibroin materials because the spatial conformation of fibroin materials is mainly maintained by hydrogen bonds between macromolecular chains. When it is immersed in water, water molecules will enter the amorphous region of fibroin and break the hydrogen bonds between molecular chains. The breakage of hydrogen bonds causes the molecular chains to transform into a random coil structure, increasing the plasticity of fibroin. When an external traction force is applied to the fibroin material, the macromolecular chains are oriented along the direction of the external traction force, and it is maintained in the externally stretched state and dried. After drying, the hydrogen bonds between the molecular weights will re-bond, and the molecular structure of fibroin is stabilized in the state before stretching. Therefore, the present application uses a wet stretching and fixing process to treat the initial fibroin rod, so that the stretched fibroin rod has a hydration-responsive contraction characteristic.

[0048] Step S4: Perform secondary machining on the stretched silk fibroin rod to obtain the target silk fibroin bone nail.

[0049] Specifically, perform secondary machining on the obtained stretched silk fibroin rod to obtain the target silk fibroin bone nail. The target silk fibroin bone nail is prepared according to the actual requirements of the specific implementation. The stretched silk fibroin rod is machined to obtain bone nails that meet any size and shape requirements.

[0050] In the embodiment of the present application, the wet stretching and fixing process includes:

[0051] Use ultrapure water to wet the initial silk fibroin rod.

[0052] Fix the initial silk fibroin rod on a tensile testing machine and stretch the initial silk fibroin rod according to the target stretching parameters. The target stretching parameters include: stretching length and stretching speed.

[0053] Specifically, during the stretching process of the initial silk fibroin rod, the stretching length and stretching speed play an important role in the shrinkage performance of the silk fibroin rod. Exemplarily, the silk fibroin rod is left standing in ultrapure water for 3 days to be fully wetted. The present application does not make specific requirements on the wetting time and can be set according to the specific test situation to ensure that the silk fibroin rod is fully wetted. Please refer to Figure 2 , Figure 2 is a schematic diagram of a stretching process. Both ends of the fully wetted silk fibroin rod are fixed on the upper and lower fixtures of a tensile testing machine, and the length of the stretching area is recorded and used as a reference to calculate the stretching length corresponding to the required stretching rate. The present application does not make specific limitations on the stretching rate, and the stretching rate can exceed 100% at most. However, in order to ensure that the rod does not break due to internal stress during drying after stable stretching, preferably, the stretching rate range is 0 - 100%. The present application does not make specific limitations on the stretching speed, and the stretching speed can be determined according to the specific implementation needs. Among them, preferably, the stretching speed range is 0 - 200 mm / min to prepare bone nails with better water and response shrinkage performance. It should be noted that the stretching rate is equal to the stretching length divided by the length before stretching, and the stretching length is equal to the length after stretching minus the length before stretching. By adjusting the stretching rate of the silk fibroin rod, the shrinkage performance of the silk fibroin can be adjusted and controlled to meet different clinical needs. In the embodiment of the present application, slow stretching is performed by controlling the stretching speed, and after reaching the target stretching rate, it is dried at room temperature to maintain a stable structure and avoid breakage of the silk fibroin structure. If the stretching speed is too large, although the target stretching rate can be reached, the material rod shows non-uniformity after stretching, and the thickness of the stretching area of the rod is significantly non-uniform. Therefore, slow and uniform stretching is considered.

[0054] In an embodiment of the present application, after stretching the initial silk fibroin rod according to the target stretching parameters, the method further includes:

[0055] Fix the stretched silk fibroin rod on a tensile testing machine and perform a drying treatment on the stretched silk fibroin rod.

[0056] Specifically, in the present application, when an external traction force is applied to the silk fibroin rod, the macromolecular chains are oriented along the direction of the external traction force, and it is maintained in the state of external force stretching and dried. After drying, the hydrogen bonds between its molecular weights will recombine, and the molecular structure of the silk fibroin is stabilized in the state before stretching. Since the rod has an elastic recovery phenomenon after stretching, it needs to be fully dried to fix the stretched shape and then removed. After the stretching of the silk fibroin rod is completed, it is fixed on the fixture of the tensile machine for drying treatment. Exemplarily, it is taken out after drying at room temperature for 3 days to obtain a silk fibroin rod with a hydration-responsive shrinkage property.

[0057] In an embodiment of the present application, the pretreatment of the silk raw material to obtain the target silk fibroin solution includes:

[0058] Perform degumming treatment on the cocoon to obtain degummed silk;

[0059] Perform a cleaning treatment on the degummed silk to obtain cleaned silk;

[0060] Provide a solvent to dissolve the cleaned silk to obtain an initial silk fibroin solution;

[0061] Perform a purification treatment on the initial silk fibroin solution to obtain the target silk fibroin solution.

[0062] Specifically, the specific implementation steps and conditions of this pretreatment can be specifically set according to the actual preparation situation. First, perform degumming treatment on the cocoon after removing the silkworm pupa to remove the sericin in the cocoon, then perform a cleaning treatment to obtain clean silk, and then dissolve the silk with a salt solution to obtain an initial silk fibroin solution. Then, perform a purification treatment on the initial silk fibroin solution. The purpose of this purification treatment is to obtain a target silk fibroin solution with a pure target molecular weight from the initial silk fibroin solution.

[0063] In an embodiment of the present application, performing degumming treatment on the cocoon to obtain degummed silk includes:

[0064] Provide an alkaline solution;

[0065] Place the cocoon in the alkaline solution and heat it to boiling for degumming to obtain degummed silk.

[0066] Specifically, the alkaline solution can be an aqueous solution prepared from sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide or other alkaline substances, which can be specifically selected according to actual needs. By placing the cocoon in the alkaline solution and heating it to boiling, the purpose of removing sericin can be achieved. During the degumming process, the present application does not specifically limit the degumming time, which can be determined according to specific experimental conditions. The duration of boiling determines the degumming time. Different degumming times affect the chain length of the silk protein molecular chain. It should be noted that in the present application, the degumming time is calculated as the duration of boiling. Preferably, the degumming time is 5 min to 5 h.

[0067] In the embodiment of the present application, the alkaline solution includes an aqueous solution of sodium carbonate;

[0068] The mass concentration of sodium carbonate in the aqueous solution of sodium carbonate is 0 to 100 g / L;

[0069] The mass ratio of the cocoon to the volume of the aqueous solution of sodium carbonate is 10:(1 - 100) g / L.

[0070] Specifically, within the range of the mass concentration of sodium carbonate in the aqueous solution of sodium carbonate being 0 to 100 g / L and the mass ratio of the cocoon to the volume of the aqueous solution of sodium carbonate being 10:(1 - 100) g / L, an aqueous solution of sodium carbonate with a suitable mass concentration and the mass ratio of the cocoon to the volume of the aqueous solution of sodium carbonate can be selected according to specific requirements for degumming treatment. Sodium carbonate is a weak base, and the aqueous solution of sodium carbonate can effectively destroy sericin protein. Moreover, compared with using stronger alkaline chemicals (such as sodium hydroxide or potassium hydroxide), sodium carbonate is a safer and more environmentally friendly choice. Therefore, by selecting an aqueous solution of sodium carbonate as the alkaline solution for degumming the cocoon, the conditions are mild and the degumming effect is good.

[0071] In the embodiment of the present application, the solvent includes an aqueous solution of lithium bromide;

[0072] The mass concentration of lithium bromide in the aqueous solution of lithium bromide is 0.01 to 2 g / mL.

[0073] Specifically, the solvent can be selected as an enzyme solution or a salt solution. In specific implementation, it can be selected according to actual conditions. Exemplarily, by selecting an aqueous solution of lithium bromide as the solvent, the purpose of completely dissolving the cleaned silk to obtain an initial silk protein solution can be achieved. Among them, the mass concentration of lithium bromide is 0.01 to 2 g / mL.

[0074] In the embodiment of the present application, the purification treatment includes:

[0075] Providing a dialysis bag and a centrifuge tube;

[0076] Transfer the initial silk fibroin solution into a dialysis bag, place the dialysis bag containing the initial silk fibroin solution in deionized water, and perform dialysis treatment on the initial silk fibroin solution to obtain the dialyzed silk fibroin solution;

[0077] Transfer the dialyzed silk fibroin solution into a centrifuge tube;

[0078] Place the centrifuge tube containing the dialyzed silk fibroin solution in a centrifuge for centrifugation, and collect the supernatant.

[0079] Specifically, select a dialysis bag with a suitable specification according to actual needs to perform dialysis on the initial silk fibroin solution. The specification of the dialysis bag is not limited in this application, and it can be selected according to the specific actual needs in the experiment. For the dialysis method, it can be static dialysis in deionized water or dialysis by stirring. Exemplarily, dialysis is performed by magnetic stirring to accelerate the dialysis speed; then the dialyzed silk fibroin solution after dialysis treatment is centrifuged. This step is a further purification treatment. Among them, the supernatant is the silk fibroin solution required in this application.

[0080] In the embodiment of the present application, after collecting the supernatant, the method further includes:

[0081] Concentrate the supernatant to obtain the target silk fibroin solution, and the mass fraction of silk fibroin in the target silk fibroin solution is 0.5% - 50%.

[0082] Specifically, since the concentration of silk fibroin in the supernatant after dialysis and centrifugation is too low to be directly used for processing and shaping, that is, it is necessary to concentrate to obtain the target silk fibroin solution. Considering that too high a concentration of silk fibroin is also not conducive to shaping, the mass fraction of silk fibroin in the target silk fibroin solution obtained by concentration is 0.5% - 50% to facilitate the subsequent preparation of silk fibroin bone nails. The present application does not make specific limitations on the concentration method, and vacuum concentration can be selected, or other concentration methods can be selected according to actual needs.

[0083] In the embodiment of the present application, a bone nail is provided, including the bone nail prepared by any method disclosed in the embodiment of the present application.

[0084] The present invention will be described in detail below through examples.

[0085] Example 1

[0086] This example is used to illustrate a preparation method and a bone nail of the present invention.

[0087] The silkworm cocoons from which the silkworm pupae have been removed are shredded as silk raw materials. 10 g of the silk raw materials are placed in a sodium carbonate aqueous solution with a volume of 20 L and heated to boiling for 30 min for degumming treatment, that is, the degumming time is 30 min. Among them, the concentration of sodium carbonate is 2.12 g / L, and the degummed silk is obtained. The degummed silk is immersed in deionized water and washed multiple times by magnetic stirring to wash away the residual sodium carbonate. After the washing is completed, it is dried to obtain the cleaned silk. The cleaned silk is placed in a lithium bromide solution with a concentration of 0.807 g / mL and kept at a constant temperature for a certain time to completely dissolve the cleaned silk in the lithium bromide solution, obtaining an initial silk protein solution, where the dissolution time is 6 h. The initial silk protein solution is filled into a clean dialysis bag and then placed in deionized water and dialyzed by magnetic stirring to accelerate dialysis. The dialysis time is 48 h, and the deionized water is changed every 7 h. Among them, the dialysis bag specification is 150 kDa, and the target molecular weight of the obtained silk protein is about 200 kDa - 350 kDa. After dialysis is completed, the solution in the dialysis bag is centrifuged in a centrifuge. Among them, the centrifuge is set with a centrifugal force of 13000 G and a centrifugation time of 30 min. Then, the supernatant is collected and concentrated to obtain a target silk protein solution with a mass fraction of silk protein of 7.5% (wt). The target silk protein solution is placed in a specific mold for drying and demolding, and processed into a cylindrical silk protein rod by a specific cutting process. Wet stretching fixation is carried out on the silk protein rod: the cylindrical silk protein rod is left standing in ultrapure water at room temperature for 3 days to be fully wetted. Then, both ends of the rod are fixed on the upper and lower clamps of a tensile testing machine, and the length of the stretching area is recorded and used as a reference to calculate the stretching length corresponding to the required stretching rate. Among them, the stretching rate is 50% and the stretching speed is 5 mm / min. After stretching is completed, it is fixed on the tensile machine clamp and dried for 3 days at room temperature and an environmental humidity of about 30% to obtain a silk protein rod with water-responsive shrinkage characteristics. The contractible silk protein rod is processed into a target silk protein bone nail by a cutting process. The length of the target silk protein bone nail is 15.5 mm. After the target silk protein bone nail is immersed in water for 24 h, the length is 13.3 mm, and the shrinkage value after 24 h is 2.2 mm. Among them, for the schematic diagram of the length comparison of the target silk protein bone nail before and after being immersed in water, please refer to Figure 3 , it should be noted that Figure 3 the ruler in

[0088] Example 2

[0089] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0090] Compared with Example 1, the elongation rate is 25%, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 hours, the length is 13.9 mm, and the shrinkage value after 24 hours is 1.6 mm.

[0091] Example 3

[0092] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0093] Compared with Example 1, the elongation rate is 75%, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 hours, the length is 12.7 mm, and the shrinkage value after 24 hours is 2.8 mm.

[0094] Example 4

[0095] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0096] Compared with Example 1, the elongation rate is 100%, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 hours, the length is 13.7 mm, and the shrinkage value after 24 hours is 1.8 mm.

[0097] Example 5

[0098] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0099] Compared with Example 1, the elongation rate is 150%, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 hours, the length is 14.9 mm, and the shrinkage value after 24 hours is 0.6 mm.

[0100] Example 6

[0101] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0102] Compared with Example 1, the stretching speed is 200 mm / min, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 hours, the length is 15.0 mm, and the shrinkage value after 24 hours is 0.5 mm.

[0103] Example 7

[0104] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0105] Compared with Example 1, the stretching speed is 20 mm / min, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 hours, the length is 14.3 mm, and the shrinkage value after 24 hours is 1.2 mm.

[0106] Example 8

[0107] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0108] Compared with Example 1, the stretching speed is 2 mm / min, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length is 13.0 mm, and the shrinkage value after 24 h is 2.5 mm.

[0109] Example 9

[0110] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0111] Compared with Example 1, the stretching speed is 220 mm / min, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length is 15.1 mm, and the shrinkage value after 24 h is 0.4 mm.

[0112] Example 10

[0113] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0114] Compared with Example 1, the degumming time is 5 min, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length is 14.6 mm, and the shrinkage value after 24 h is 0.9 mm.

[0115] Example 11

[0116] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0117] Compared with Example 1, the degumming time is 2 min, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length is 15.1 mm, and the shrinkage value after 24 h is 0.4 mm.

[0118] Example 12

[0119] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0120] Compared with Example 1, the degumming time is 10 min, and other conditions remain unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length is 13.9 mm, and the shrinkage value after 24 h is 1.6 mm.

[0121] Example 13

[0122] This example is used to illustrate a method for preparing a bone nail and the bone nail of the present invention.

[0123] Compared with Example 1, the degumming time was 20 min, and other conditions remained unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length was 13.7 mm, and the shrinkage value after 24 h was 1.8 mm.

[0124] Example 14

[0125] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0126] Compared with Example 1, the degumming time was 60 min, and other conditions remained unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length was 13.4 mm, and the shrinkage value after 24 h was 2.1 mm.

[0127] Example 15

[0128] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0129] Compared with Example 1, the degumming time was 120 min, and other conditions remained unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length was 13.9 mm, and the shrinkage value after 24 h was 1.6 mm.

[0130] Example 16

[0131] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0132] Compared with Example 1, the degumming time was 5 h, and other conditions remained unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length was 14.9 mm, and the shrinkage value after 24 h was 0.6 mm.

[0133] Example 17

[0134] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0135] Compared with Example 1, the mass fraction of silk fibroin in the target silk fibroin solution was 0.5% (wt), and other conditions remained unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length was 14.1 mm, and the shrinkage value after 24 h was 1.4 mm.

[0136] Example 18

[0137] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0138] Compared with Example 1, the mass fraction of silk fibroin in the target silk fibroin solution was 4% (wt), and other conditions remained unchanged. After immersing the target silk fibroin bone nail in water for 24 h, the length was 13.4 mm, and the shrinkage value after 24 h was 2.1 mm.

[0139] Example 19

[0140] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0141] Compared with Example 1, the mass fraction of silk fibroin in the target silk fibroin solution is 50% (wt), and other conditions remain unchanged. After the target silk fibroin bone nail is immersed in water for 24 h, the length is 13.8 mm, and the shrinkage value after 24 h is 1.7 mm.

[0142] Example 20

[0143] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0144] Compared with Example 1, the mass concentration of lithium bromide is 2 g / mL, and other conditions remain unchanged. After the target silk fibroin bone nail is immersed in water for 24 h, the length is 13.9 mm, and the shrinkage value after 24 h is 1.6 mm.

[0145] Example 21

[0146] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0147] Compared with Example 1, the mass concentration of sodium carbonate is 100 g / L, and other conditions remain unchanged. After the target silk fibroin bone nail is immersed in water for 24 h, the length is 13.5 mm, and the shrinkage value after 24 h is 2.0 mm.

[0148] Example 22

[0149] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0150] Compared with Example 1, 10 g of silk raw material is placed in an aqueous sodium carbonate solution with a volume of 100 L, and other conditions remain unchanged. After the target silk fibroin bone nail is immersed in water for 24 h, the length is 13.4 mm, and the shrinkage value after 24 h is 2.1 mm.

[0151] Example 23

[0152] This example is used to illustrate a preparation method of a bone nail and the bone nail of the present invention.

[0153] Compared with Example 1, 10 g of silk raw material is placed in an aqueous sodium carbonate solution with a volume of 10 L, and other conditions remain unchanged. After the target silk fibroin bone nail is immersed in water for 24 h, the length is 13.3 mm, and the shrinkage value after 24 h is 2.2 mm.

[0154] Comparative Example 1

[0155] The silk cocoons from which the silkworm pupae have been removed are shredded as silk raw materials. 10 g of the silk raw materials are placed in a sodium carbonate aqueous solution with a volume of 20 L and heated to boiling for 30 min for degumming treatment. Among them, the concentration of sodium carbonate is 2.12 g / L, and the degummed silk is obtained. The degummed silk is immersed in deionized water and washed multiple times by magnetic stirring to wash away the residual sodium carbonate. After the washing is completed, it is dried to obtain the cleaned silk. The cleaned silk is placed in a lithium bromide solution with a concentration of 0.807 g / mL and kept at a constant temperature for a certain time to completely dissolve the cleaned silk in the lithium bromide solution, obtaining an initial silk fibroin solution, where the dissolution time is 6 h. The initial silk fibroin solution is filled into a clean dialysis bag and then placed in deionized water for accelerated dialysis by magnetic stirring. The dialysis time is 48 h, and the deionized water is changed every 7 h. Among them, the dialysis bag specification is 150 kDa, and the target molecular weight of the obtained silk fibroin is about 200 kDa - 350 kDa. After dialysis is completed, the solution in the dialysis bag is centrifuged in a centrifuge. Among them, the centrifuge is set with a centrifugal force of 13,000 G and a centrifugation time of 30 min. Then, the supernatant is collected and concentrated to obtain a target silk fibroin solution with a mass fraction of silk fibroin of 7.5% (wt). The target silk fibroin solution is placed in a specific mold for drying and demolding, and processed into a silk fibroin bone nail through a specific cutting process. The length of the silk fibroin bone nail is 15.5 mm. After the silk fibroin bone nail is immersed in water for 24 h, the length is still 15.5 mm, and the shrinkage value after 24 h is 0 mm.

[0156] As can be seen from the above technical solutions of the embodiments of the present invention, a preparation method of a bone nail disclosed by the present invention includes first pre-treating silk raw materials to obtain a target silk fibroin solution; shaping, drying and demolding, and first machining the target silk fibroin solution to prepare an initial silk fibroin rod; performing a wet stretching and fixing process on the initial silk fibroin rod to obtain a processed silk fibroin rod; and performing second machining on the processed silk fibroin rod to obtain a target silk fibroin bone nail. Through the wet stretching and fixing process on the silk fibroin rod, the target silk fibroin bone nail prepared based on the stretched silk fibroin rod has a hydration-responsive shrinkage characteristic, can slowly shrink in vivo, provide compressive force, promote bone reduction, stimulate bone healing, has wide applicability and low cost.

[0157] The above description has fully disclosed the specific embodiments of the present invention. It should be noted that any modification made by those skilled in the art to the specific embodiments of the present invention does not depart from the scope of the claims of the present invention. Correspondingly, the scope of the claims of the present invention is not limited only to the foregoing specific embodiments.

Claims

1. A method for preparing a bone screw, characterized in that: The method comprises: Pre-treating the silk raw material to obtain a target silk protein solution; The target silk protein solution is subjected to shaping, drying, demoulding and first mechanical processing in sequence to obtain an initial silk protein rod; The initial silk protein rod is subjected to a wet stretching and fixing process to obtain a stretched silk protein rod; The stretched silk protein rod is subjected to a second mechanical processing to obtain the target silk protein bone nail.

2. The method according to claim 1, characterized in that The wet stretching and fixing process comprises: Using ultrapure water to wet the initial silk protein rod; The initial silk protein rod is fixed on a tensile testing machine, and the initial silk protein rod is stretched according to target stretching parameters; the target stretching parameters include: stretching length and stretching speed.

3. The method according to claim 2, characterized in that After stretching the initial silk protein rod according to the target stretching parameters, the method further includes: The stretched silk protein rod is fixed on the tensile testing machine, and the stretched silk protein rod is dried.

4. The method according to claim 1, characterized in that: The pre-treating of the silk raw material to obtain the target silk protein solution comprises: Degumming the silk cocoons to obtain degummed silk; Cleaning the degummed silk to obtain cleaned silk; Providing a solvent to dissolve the cleaned silk to obtain an initial silk protein solution; The initial silk protein solution is purified to obtain the target silk protein solution.

5. The method according to claim 4, characterized in that The degumming of silk cocoons to obtain degummed silk comprises: providing an alkaline solution; The silk cocoons are placed in the alkaline solution and heated and boiled for degumming to obtain the degummed silk.

6. The method according to claim 5, characterized in that The alkaline solution includes an aqueous solution of sodium carbonate; The mass concentration of sodium carbonate in the sodium carbonate aqueous solution is 0 to 100 g / L; The volume ratio of the mass of the silk cocoons to the sodium carbonate aqueous solution is 10: (1-100) g / L.

7. The method according to claim 4, characterized in that The solvent includes an aqueous solution of lithium bromide; The mass concentration of lithium bromide in the lithium bromide aqueous solution is 0.01-2 g / mL.

8. The method according to claim 4, characterized in that The purification process comprises: Provide dialysis bags and centrifuge tubes; Transferring the initial silk protein solution to the dialysis bag, placing the dialysis bag containing the initial silk protein solution in deionized water, and dialyzing the initial silk protein solution to obtain a dialyzed silk protein solution; Transferring the dialyzed silk protein solution to the centrifuge tube; The centrifuge tube containing the dialyzed silk protein solution is placed in a centrifuge for centrifugation, and the supernatant is collected.

9. The method according to claim 8, characterized in that After collecting the supernatant, the method further comprises: The supernatant is concentrated to obtain the target silk protein solution, wherein the mass fraction of silk protein in the target silk protein solution is 0.5% to 50%.

10. A bone screw, characterized in that: The present invention comprises a bone screw prepared by the method according to any one of claims 1 to 9.

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